For correct diagnosis of various cancer diseases biopsies are taken. This can either be done via a lumen of an endoscope or via needle and catheter biopsies. An example of a needle biopsy is shown in FIG. 1, where a biopsy is taken from the prostate via the rectum. In order to find the correct position to take the biopsy, various imaging modalities are used such as X-ray, CT, MRI and ultrasound. In case of prostate cancer in most cases the biopsy is guided by ultrasound (see FIG. 1). Although helpful, these methods of guidance are far from optimal.
There are problems directly related to the biopsy:
The resolution of the imaging system is limited and, furthermore, these imaging modalities cannot in most cases discriminate normal and neoplastic tissue and further differentiate between benign and malignant tissue.
As a result of that, there is a high level of uncertainty whether an appropriate tissue specimen is taken.
In addition to that, the biopsies are often taken blindly, with limited feedback of where the needle is relative to the target tumor, which leads to an additional uncertainty whether the lesion has been hit by the needle. It is clear that guidance improvement is required to target the biopsy needle to the correct position in the tissue.
A way to solve the navigation towards the suspicious tissue is by navigating the biopsy needle tip by employing electromagnetic guidance as described in U.S. Pat. No. 6,785,571 B2. However the accuracy of the method is limited to a few millimeters. As a result for small sized suspicious tissue volumes there is a certain chance of taking the biopsy at the wrong place. A further limitation is that even if one could guide the biopsy needle to the exact location corresponding to the pre-recorded image, one is never sure that this is the exact location due to the compressibility of the tissue. Due to the force of the biopsy needle on the tissue during advancement, the tissue may become deformed.
If the specimen taken appears to be cancerous, in most cases this cancerous tissue will be removed by surgery (especially when the tumor is well localized) or treated percutaneously using RF, microwave, or cryoablation.
The surgical approach is confounded by the fact that the surgeons typically use only their eyes and hands (palpation) to find the tumor and have to rely on the information of pre-recorded images. These pre-recorded images provide information on the position of the tumor but do not always clearly show the tumor boundaries. Sometimes, the surgeon implants a marker under image guidance, providing him or her with a reference point to focus on during the surgical procedure. Again guiding the localization wire to the correct position is difficult.
It is particularly difficult to find the boundaries of the tumor, in fact it is virtually impossible. As a result of that, the surgeon removes a significant amount of tissue around the core of the tumor to make sure that the entire tumor mass is removed. Although removing an additional amount of tissue around the tumor will indeed lead in most cases to complete removal, the surgeon is never sure. The number of recurrences of the cancer after removal is 30%, which indicates that some parts of the tumor remained in place and caused further tumor re-growth. One could of course increase the amount of tissue to be removed but this in several cases difficult. In some cases vital structure are present in the tissue (nerves, important blood vessels, brain tissue). The surgeon has then to decide whether the malfunctioning due to the removal of additional healthy tissue outweighs the risk of not completely removing the tumor. It is important to note that when resection is not complete, the surgeon has, in fact, cut through the tumor and may cause further dissemination of the tumor.
The biopsy device may also be used as a device for administering drugs or a therapy (like ablation) at a certain position in the body without removing tissue, for instance for injecting a fluid at the correct location of the affected body part. The same drawbacks apply for these interventions where it is difficult to guide the biopsy device to the correct location.
The current way of working to take a biopsy has some drawbacks, including:                difficult to guide the biopsy needle to a centre of the tissue to be investigated;        difficult to delineate the tumor boundaries (shape and size of tumor); and        taking specimen out of the body for the histological analysis may cause further dissemination of the tumor.        